Recently, ALD (Atomic Layer Deposition) capable of forming a thin film for each of atomic and molecular layers is receiving attention as a technique having various features including one capable of forming a high-quality thin film more uniformly at a temperature as low as about 300° C. The ALD method is an epitaxial growth technique of forming a thin film for each atomic layer by alternately supplying, to a substrate, the source gases of respective elements which constitute a film to be formed.
In the formation of a thin film using the ALD method, for example, the gas of an organic compound of a metal which constitutes a film to be formed is used as a source gas. Most organic metal compounds are liquids at room temperature (about 20° C.). Thus, an epitaxial growth technique such as ALD evaporates a liquid of an organic metal compound by so-called bubbling and uses it as a source gas (Japanese Patent Laid-Open Nos. 5-074758 and 5-251348). The method of evaporating a liquid raw material by bubbling is a simply raw material supply means for evaporating and supplying a liquid raw material because the structure is simple and a gas used for bubbling can be used as a carrier gas for an evaporated source gas.